This invention relates in general to clamping devices and, in particular, to a clamping device which in one embodiment is especially suitable for use as a pedestal clamp for grounding to buried residential meter boxes or a panel ground clamp, and in another embodiment is especially useful for joining or coupling two flat pieces or straps of material.
More specifically, but without restriction to the particular embodiments and/or use which are shown and described for purposes of illustration, this invention relates to a clamp having a U-shaped portion with one side of the U supporting a hardened pointed tip, and the opposing side of the U supporting a threaded bolt having a complementary cup-shaped recess for mechanically and electrically connecting the clamp to a flat panel or structure, or joining two flat pieces of strap material positioned therebetween.
As is known to those skilled in the art, various clamping devices have been utilized to provide an electrical ground or to join flat bar stock, such as copper bars used in various grounding devices. In applications wherein a pipe or conduit, for example, is to be grounded a grounding clamp such as disclosed in the inventor's U.S. Pat. No. 4,626,051 and co-pending application Ser. No. 94,268, filed Sept. 8, 1987, permit the grounding of various sized pipes or conduits without subjecting the clamping strap to false torques or damage which had been occasioned by prior art devices. While the clamps disclosed in the above-identified patent and pending application have been very successful in grounding pipes and conduits, such devices were not intended to be used for grounding panels or joining straps of grounding material.
In many applications, especially in residential housing construction, electrical service is provided through metered service. The meters by which the amount of service is determined are contained within a meter box, the base of which is many times partially buried in the ground. If a suitable grounding clamp could be utilized, the buried residential meter box can be used for coupling a terminated ground wire. The ground wire could then be fed through the conduit into the house for forming the necessary ground connection.
The problems, however, with utilizing a buried residential meter box for this purpose is that the part of the box to which a clamp would be most readily attachable is buried underground. Such boxes, also, are painted and/or treated with a coating to preserve them. Therefore, a grounding clamp must be capable of attachment in adverse conditions wherein dirt, paint, etc, must be removed at the point of attachment to ensure a suitable mechanical and electrical connection. If these problems can be overcome, the buried residential metal box becomes a suitable ground, eliminating the necessity heretofore required of sinking a grounding rod into the ground for forming such a ground connection.
In other applications, such as the installation of phone service to a mobile home, it is also desirable that the structure of the home be properly connected to ground by appropriately terminated ground wire. In connecting such a terminated ground wire to the home, the connection also must be done in a proper manner to ensure an effective electrical connection between the home and the terminated ground wire. In the construction of such homes, a metal frame and exterior is generally utilized. The metal frames generally are formed from channels or with flanges which are suitable for grounding purposes.
One embodiment of the present invention is especially suitable for mechanically and electrically connecting a terminated ground wire to buried residential meter boxes and mobile homes. The other embodiment of this invention is more suitable for mechanically and electrically connecting two flat pieces of strap material such as, for example, two copper bars which may be suitable for a terminated ground connection.
The clamps of the present invention are substantially U-shaped and have a pointed cone-shaped portion extending outwardly from one inner surface of the clamp towards the other, with a threaded bolt or stud having a complementary cup-shaped recessed portion in the end thereof extending outwardly from the opposed inner surface of the clamp. In this manner, when a piece of material is positioned within the bight of the U-shaped clamp, and the threaded bolt turned towards engagement with the oppositely positioned cone-shaped tip, the material therebetween will be engaged. Depending upon the relative hardness between the materials of the cone-shaped tip and the threaded bolt, and the material entrapped therebetween, the entrapped material will be mechanically worked by the two portions of the clamp to ensure a reliable mechanical and electrical coupling of the material sandwiched therebetween. Preferably, the material to be entrapped is less hard than the material from which the threaded bolt and cone tip are formed, so that upon tightening of the clamp, the cone tip will be forced into the material, deforming the material into the cup-shaped recess to ensure a proper connection. The edge of the cup-shaped portion will work or abrade against this material removing any dirt, paint, rust or coatings to ensure contact with the base metal.